10min:
CAVITY RING-DOWN LASER ABSORPTION SPECTROSCOPY OF THE E 3 Delta - X 3 Delta TRANSITION OF VN.

TONGMEI MA, J. W-H. LEUNG AND A. S-C. CHEUNG, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong.

The (0,0) band of the electronic transition of VN at around 450.5 nm has been investigated using the technique of laser vaporization/reaction with free jet expansion and cavity ring-down laser absorption spectroscopy. A new transition system was observed, which has been designated as the E 3 Delta - X 3 Delta system. All three Delta Omega = 0 subband transitions were recorded and rotationally analyzed. Least squares fit of the measured line positions yielded molecular constants for the new E 3 Delta state. The bond length of the E3 Delta state was determined to be 1.6937 Å, which is the longest among the known states of VN. The E 3 Delta state is expected to arise from an electronic configuration 1 delta1 10 sigma1 where the 10 sigma orbital is an antibonding orbital. A comparison of the observed electronic states of the isoelectronic TiO molecule supports the assignment.